1. Field
Example embodiments relate to an apparatus and a method of determining a weighting function quantizing linear prediction coding (LPC) coefficients.
2. Description of the Related Art
Conventionally, linear prediction coding (LPC) is applied to coding speech signals and audio signals. Code-excited linear prediction (CELP) is used for LPC and uses an LPC coefficient and an excitation signal with respect to an input signal. When the input signal is coded, the LPC coefficient may be quantized. However, when the LPC coefficient is quantized as is, a resulting dynamic range is narrow and identification of stability is difficult.
When all LPC coefficients are quantized on the same importance in order to select a codebook index to reconstruct an input signal in a decoding process, quality of a finally synthesized input signal may deteriorate. Since all LPC coefficients have different weightings, the finally synthesized input signal is improved in quality when an important LPC coefficient has fewer errors. However, when a difference in weighting is not considered and the same weighting is applied in quantization, quality of the input signal deteriorates.
Thus, there is a demand for a method of efficiently quantizing an LPC coefficient and improving quality of a synthesized signal when the input signal is reconstructed by a decoding apparatus.